The present invention relates generally to locomotive brake controls, and more specifically to a locomotive brake control which has holding and/or blending.
Power brake equipment for locomotives has typically been implemented with mechanical and pneumatic hardware, for example, the 26-L brake equipment from New York Air Brake Corporation of Watertown, N.Y. The prior art brake equipment employs as major components, 26-C brake valve, including an independent brake valve SA-26, 26-F control valve and a J-relay which controls the brake cylinder on the locomotive. An automatic brake handle controls the train brakes through the brake pipe. An independent brake handle independently controls the locomotive brakes. The independent brake handle also includes a bail-off feature for bailing off or release of any automatic brake application on the locomotive brake. A throttle controls the propulsion of the locomotive and train and includes dynamic braking of the locomotive. Such equipment is illustrated in FIGS. 1 and 2 of U.S. Pat. No. 5,590,042.
Electropneumatic control of this equipment has been suggested by the prior art. Computerization of the locomotive brake control taking into consideration the independent brake, the automatic brake and bail-off from the automatic brake is described in U.S. Pat. No. 5,590,042 which is incorporated herein by reference. Such a system does not include a hold feature nor does it take into account any dynamic braking.
A locomotive control system which takes into account manual bail-off from the independent brake handle as well as the dynamic bail-off is described in U.S. Pat. Nos. 5,286,096 and 5,385,392. If a manual or a dynamic bail-off is present and there is no emergency braking, a non-recoverable bail-off is conducted. This requires an additional brake application before the brakes are reapplied. If a manual bail-off or dynamic bail-off is present and there is an emergency condition, recoverable bail-off is conducted. Although the system monitors the dynamic bail-off to determine whether there is a recoverable or non-recoverable bail-off, it does not blend the dynamic bail-off signal with the pneumatic braking signal. Also, it does not disclose the use of a hold feature.
Other pneumatic prior art system includes the number 6-BL brake equipment. This includes an H-6 automatic brake valve and an LA-6-P independent brake valve for controlling the brake equipment. Different from the 26 brake equipment, the H-6 automatic brake handle includes the release running, holding, lap, service and emergency positions. The release and running positions are effectively both release of the train brakes for charging the brake pipe and releasing the train brakes. The hold position is a position which holds the brakes on the locomotive while allowing the train brakes to be released and their auxiliary reservoirs and brake pipe recharged. The service position gives a gradual reduction of brake pipe pressure to cause a service application and the emergency position results in a prompt and heavy application of the brakes. The lap position is used to hold the train brakes applied after a service application. This is purely a mechanical pneumatic system and includes no blending or computerized control.
The brake control system of the present invention is a system for a locomotive which has a propulsion control cable of dynamic braking and a brake cylinder. The system includes an input receiving train brake signals, bail signals, hold signals and blending signals. A computer determines a brake cylinder pressure control signal from the train brake signal, the bail signal, the hold signal and the blending signal. The pressure in the brake cylinder is controlled in response to the brake cylinder control pressure. Typically, the train brake signal and the bail signal are pneumatic signals which may be received from the brake pipe and the 13 or actuating pipe respectfully. The hold signal and blending signal are electric signals. The train brake and bail pneumatic signals are converted to electric signals.
A brake cylinder pressure control signal or a preliminary brake cylinder pressure control signal is determined from the train brake signal and the bail signal. A hold pressure control signal and a blending pressure control signal can also be determined. The pressure in the brake cylinder is then controlled in response to one of the brake cylinder pressure control signal, the hold pressure control signal and a blending pressure control signal. All three of these pressure control signals can be used to control pressure in a respective reservoir. The reservoir may be an actual reservoir or a simulation of the characteristics of a reservoir changed to the pressure value represented by the pressure control signal. The determination of the brake cylinder pressure control signal includes determination of the rate of change of pressure as well as a final pressure value.
Wherein a preliminary brake control pressure signal is determined from the train brake signal and the bail signal, it is provided to the propulsion control system. The propulsion control system then provides a blending signal in response to the preliminary brake control signal and dynamic braking. The brake cylinder is then controlled based on this blended signal. Also, a brake cylinder control signal to reduce the brake cylinder pressure to zero is determined in response to a bail signal. After removal of the bail signal, a brake cylinder control signal is determined to increase the brake cylinder pressure if an emergency brake signal is received before the bail signal or a service brake signal is received after removal of the bail signal. A brake cylinder pressure control signal is determined, which maintains the pressure of the brake signal at its value upon receipt of a hold signal. The hold signal is disregarded if it is present at the same time as a bail signal.
The brake control system for a locomotive may also receive a train brake signal, a bail signal and a hold signal and determine a brake cylinder pressure control signal from the train brake signal, the bail signal and the hold signal. The brake cylinder is controlled in response to the brake cylinder pressure control signal. Similarly, a brake control system for a locomotive having a propulsion control capable of dynamic braking can receive a train brake signal, a bail signal and a blending signal. A preliminary brake control signal is determined from the train brake signal and the bail signal and provided to the propulsion control system. The propulsion control system provides a blending signal responsive to a preliminary brake control pressure signal and dynamic braking. A brake cylinder pressure control signal is determined from the train brake signal, the bail signal and the blending signal and is used to control the pressure in the brake cylinder. Thus, the locomotive brake signal may be controlled using a train brake signal, a bail signal and either a hold signal or a blending signal, or both.
The present invention includes the apparatus for brake controls as well as a method for locomotive brake control.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.